Drive I/O and read errors

[nozmoking]

I apologize if this has been covered already somewhere else. I am attempting to recover data from a 1TB drive that is mounted in an external USB enclosure. The drive began throwing "Drive not formatted" errors after being subjected to a flaky power supply in another USB enclosure. I've elected to make an uncompressed image of the drive with R-Studio to reduce the risk of losing data and a simple scan with the software does reveal an intact file/directory tree. However after about 250GB and 12 hours into the image creation process the drive began to throw device I/o and read errors consistently and although it advances to the next location after 2 tries it has been in this state for many hours. My question is, should I be using some other method besides making a single-pass image of the entire 700+GB partition (NTFS) or should I try breaking the image up into smaller chunks? Also, could the USB enclosure be causing time-outs or other anomalies, and might I have better success with the drive attached directly to a SATA controller (other than speed constraints)? The host machine is a core i5 with 24 GB of RAM so it should have plenty of headroom.

Thanks

[Alt]

I don't think this is because of the USB enclosure, more likely the disk might be damaged. But I can't be sure until I see the disk and enclosure firsthand.
Direct connection through the sata is indeed faster, but I think that you'll have to start imaging again. So, I'm not sure what to do.

[nozmoking]

Thanks for the reply. The USB enclosure is actually new and was bought just to work on the bad drive. I have put several of them in to permanent service with good results. Other than speed I'm pretty sure the enclosure isn't at fault. I ended up going through the drive with R-Studio in file/directory mode and recovered most of the data. The fewer files I tried to recover at once the more success I had, and some files exhibiting read errors when recovering multiple files actually recovered intact when I repeated the recovery process on just a single file. I'll probably pull the drive out of the enclosure and connect it directly to the controller just for grins and make one last attempt at getting an image for posterity before I add its platters to my wind chime collection. All things considered I've learned a lot from the experience and also found that R-Studio is an excellent and economical tool for recovering data.